In the original conventional technology of fasteners employed to securely attach one object to another, such as for example one part to another in the case of an automobile or an appliance, has utilized a nut on one of the two objects, usually welded or glued to the back of said object, and a bolt passing through a hole on the second object in a manner to be engaged by the nut, thereby securing the two objects together.
This arrangement presents many problems, among which, one of the most important is that in the case that one object is hollow, the nut has to be in place at the back of the hollow object before assembling the two objects together. If for any reason the nut is misplaced, and/or if it becomes desirable to introduce a new fastening connection between the two objects, the task of achieving such connection becomes very difficult if not impossible for all practical purposes.
The so-called "quick nuts" have also been used to connect two objects. In addition, vibration during the operation of a device, such as an automobile or appliance for example, containing the two objects results very often in loosening of the bolt or "quick nut" and in either full disassembling of the objects from each other, or in a vibration noise which is most annoying and often of unacceptable levels. Further, such connections are not water-resistant and water may be easily penetrate the connection point and be transferred from one side of one or both objects to the other side.
Recently, fasteners of the type described in U.S. Pat. No. 4,500,238 (Vassiliou) have been utilized to reduce considerably the potential of bolt or screw loosening and vibration. They have also eliminated the problem of having to place one member of the fastener at the back portion of the hollow object. These fasteners are placed through a slot from the front part of the hollow object. An expanding member, being usually a bolt or a screw, supports the second object by forcing the legs of the fastener (as described for example in U.S. Pat. No. 4,500,238) to open or expand, thereby securing the two objects together. The legs of the fasteners are supported by a double-layered head having an upper side and a lower side joined by side bents. The fasteners of this type have greatly improved the prevailing torque, as well as the pulling force of the system. Prevailing torque is the torque required to render a screw loose. Pulling force is the pulling force applied on the screw to the point of failure, which usually occurs at the bents.
One drawback of the above fasteners is that the two layers or sides of the head separate the two objects to be connected together by a distance equal to the head thickness, unless there is a recess in at least one of the objects to nest the head. This situation is worsened by the fact that the bents joining the two layers or sides of the head should to have a curvature as high as possible in order to increase the pulling force and prevent premature failure. Thus, in many occasions it is desirable to have fasteners having a single-layered head in order to minimize the thickness of said head.
It is one object of this invention to provide such fasteners having a substantially single-layered head.